Motion tracking : setting parameter for multiple selected trackers
I would advise you not to treat all trackers the same. Not all trackers need to be in a single mode, some work better with perspective, some with loc rot, some with loc rot scale. It all depends on the kind of motion you are tracking and how the particular tracked feature moves in the video and the item's visibility. If you are learning, think of trackers as individual processes. Supervise the behavior of each tracker individually to learn how to get more accurate results.

And to answer the question, no there is no easy way to select all trackers and change the motion model for multiple trackers. It could probably be done by scripting.